Engine starter gearing



June 29, 1943.

Filed July 19, 1941 Patented June 29, 1943 UNlTiEl) T 5 FTE N T 9 Fri IENGINE STARTER GEABING Application July.19, 1941, Serial.No. 403,182

8 Claims.

The present invention relates .to enginestarter gearing and moreparticularlyto a drive for connecting 'a starting motor to a member of.an engine to be started, and maintaining said connection until theengine is reliably self-operative.

It is an object of the presentinvention to provide a starter drive whichis efficient and reliable inoperation, small in size. and simple andeconomical inconstruction. It is another object to provide such adevice.

incorporating a yielding overrunning connection.

It is a further object to provide such a device incorporating means forholding the drive in operative position as long as the starting motor isenergized.

Further objects and advantages will beapparent 4 from the followingdescription taken in connection withthe accompanying drawing in hich:

Fig. '1 is a side elevation partly in section of a starter driveembodying a preferred form of-the invention;

Fig. 2- is a section taken substantiallyon the line.2.2 of Fig. 1;

Fig. 3 is a view similar to Fig. 1 showing the a be.-provided with ahardened thrust washer 4. Thevscrew shaft I has a further reduced smoothextensionj and, ascrew-threaded element in they form of a hollowlscrewshaft 6, fixed thereon in any suitableway as by means of a cross pin],the surface of, the screw shaft being flush with the. smooth portion 2of the power shaft.

A, pinion. member 8 is slidably journalled on the;screw, shaft andsmooth portion 2 ofthe power shaft for movement into and outofengagement with amember such as a gear 9 of an engine .to be started.Pinion member 8 has aflange, member ll fixed, thereon in any suitablemanner .as ..by..brazing. A flanged nut I2 is threadedon the screwshaftB; and a torsionally resilient overrunning connection, between saidflanges is provided in the formof a (cylindrical as rubber which isadapted to frictionallyengage the flanges under the screwjack-actionjofthe screw shaft and nut.

Means for enclosing the elastic element 13 is provided in the form of asleeve 14 surroundingthe member I3 and the fiangesof the mem bers H andI2, said sleeve being provided with. an inturned lip l5 at one. end anda splitretainf ing ring [6 at the other end so arrangdoaslto limitseparation of the flange members! and; loosely confine the elasticmember l3 therebe-Q. tween.

According to the present invention, means areprovided for holdingthepinion 8 in eng agementl' with the engine gear as long. asthestarting I motor is energized. Ashere shown thismeans is in the form ofa detent or latchmember l1; mounted in the end -of the screw shaftiiand. normally maintained flush with the surfaceofthe screw shaft byyielding means such as the} split spring ring l8. When the power shaftand screw shaft are rotating above a predetermined speed, the latch I1is movedoutwardly byrcentrifugal force, and if the pinion is atthattimein engagementvwith'the engine gear, the latch;- l'l will protrude backof the pinion and prevent its return to idle position as illustrated inFig. 3.;. The latch I! is also preferably arranged to frictionallyengage the interior .of the pinion as, shown in Fig. 1, when the pinionis in idle position and thereby prevent the pinion from. drift, ingtoward the engine gear when the drive is, not in operation.

In operation, starting with the parts inu the positions illustrated inFig. 1,, actuationofthe power shaft causes the nut member llto threaditself along the screw shaft 6, which longi-.v tudinal motion istransmitted yieldingly through v the elastic member 13 to the flangemember H and pinion 8. When the pinion engages. the thrust Washer 4 onthe power shaft l, the pinion} is fully meshed with the enginegearandits longitudinal motion is arrested, whereupon fur ther longitudinalmovement of the, nut member l2 compresses the elastic member l3 so astoform a yielding self-tightening clutch- WhiChgtI'flJlfimits rotationfrom the power shaft throughthe pinion to the engine gear 9.

When the engine fires, the accelerationof the, engine gear causes thepinion 8 tooverrun the;

drive and the nut i2 is thereby accelerated and,

threads itself back along the screw shaft-L Since the starting motor isenergized, however, the power shaft is rotated with sufiicient-spee dtoy cause the latch ll to protrude frorn- .th e screw shaft in the path ofthe pinion and prevent the pinion from demeshing from the engine gear.Since the pinion is so held, while the nut member I2 is free to returntoward its idle position so far as permitted by the sleeve M, theyielding member I3 is released from the flanges as indicated in Fig. 3and the pinion member is permitted to overrun freely.

If the engine fails to continue to be self-operative, the decelerationof the engine gear permits the power shaft to overtake and drive thepinion, and cranking is resumed. When the engine becomes reliablyself-operative, the starting motor is deenergized by the operator, andwhen the rotation of the power shaft falls below the predeterminedminimum, the latch I1 is withdrawn by the spring l8 and the pinion andassociated parts are permitted to return to idle position where they arefrictionally retained by the engagement of the member I! with theinterior of the pinion.

In Fig. 5 of the drawing there is illustrated an embodiment of theinvention incorporating structure for facilitating the meshing anddriving operation of the pinion." As there shown a power shaft 2| has asmooth extension 22 providing a thrust shoulder 23, and a furtherreduced smooth extension 25 on which is mounted ascrew shaft 26 whoseexternal surface isflush with the surface of the Portion 22. chored tothe power shaft by means of a cross pin 21. A pinion member 28 isslidably joinnalled on the smoothportion' 22 of the power shaft and thescrew shaft 26 for movement into engagement with an engine gear 29.

A flange member 3| is fixed to the pinion 28 as indicated at 30, and aflange nut 32 is threaded on the screw shaft 26. A sleeve 33 of elasticmatrialsuch as rubber is seated on the nut member 32 in position toloosely engage the flange member 3|- of the pinion.

In the present embodiment of the invention a barrel member 34 isarranged to surround the elastic sleeve 33 and hold it loosely confinedbetween the flanges of members 3i and 32, and this barrel member isarranged to transmit torque directly from the elastic member 33 to thepinion 28 during the cranking operation. For this purpose the front endof the barrel 34 is provided with an inwardly extending flange 35 havingnotches cut therein adapted to slidably receive the teeth of the pinion28, so as to splinethe barrel to the pinion. A split lock ring 36 isprovided in the open end of the barrel for holding the parts inassembled position. A centrifugal detent 31 is mounted in the screwshaft 26 under the control of a spring ring 38, said detent serving asan anti-drift when the drive is idle, and also serving to hold thepinion in engagement with the engine gear as long as the power shaft isrotating above a predetermined speed.

serves to increase the torque capacity of the coupling formed by theelastic sleeve 33 due to the increased area of useful torque of saidsleeve transmitting surface. The sleeve 33 is here illustrated as havinga pilot portion bearing on the Screw shaft 26 is an- (ill 'a'seaie nutmember 32, and as being bevelled off to a substantial extent as shown at4| adjacent the open end of the barrel member 34. While these featuresare considered desirable, they are not considered essential to theinvention and it is not desired to limit the scope of the inventionthereto, nor in any other way' than as defined in the claims appendedhereto.

What is claimed is:

1. In an engine starter drive a power shaft, an engine driving memberslidably journalled thereon, a screw shaft fixed to the power shaft, anut on the screw shaft having a driving flange, a driven flange memberfixed to the engine driving member, a body of elastically deformablematerial loosely mounted between said flanges, means limiting separationof the flanges to an amount slightly greater than the free length of theelastic body, thus permitting free overrunning of the engine drivingmember, and abutment means on the power shaft engageable by the enginedriving member when in operative position to limit longitudinal movementof the engine driving member and cause the elastic body to be compressedbetween the flanges and thereby form a clutch connection between the nutand engine driving member.

2. A starter drive as set forth in claim 1 including, further, meansresponsive to rotation of the power shaft for engaging the enginedriving member to resist its return to idle position.

3. An engine starter drive as set forth in claim 1 including, further, alatch member mounted on the screw shaft movable by centrifugal force toa position to engage the engine driving member and prevent it returningto idle position.

' 4. An engine starter drive as set forth in claim 1 including, further,unitary means for resisting disengagement of the engine driving memberfrom the engine member, and for retaining the engine driving member inidle position.

5. In an engine starter drive, a power shaft having a stop shoulder, asmooth portion adjacent thereto and a screw-threaded element adjamentthe smooth portion and flush therewith a flanged pinion member slidablyjournalled on the smooth portion and screw-threaded element forlongitudinal movement into engagement with an engine ear, said shoulderon the power shaft defining the operative portion of the pinion member,a flanged nut on the screw-threaded element, a body of elasticallydeformabl material loosely mounted between said flanges, means limitingthe separation of the flange and means responsive to rotation of thepower shaft for holding the pinion in engagement with the engine gear.

6. In an engine starter drive, a power shaft having a stop shoulder, asmooth portion adjacent thereto and a screw-threaded element adjacentthe smooth portion and flush therewith, a. flanged pinion memberslidably journalled on the smooth portion and screw-threaded element forlongitudinal movement into engagement with an engine gear, said shoulderon the power shaft defining the operative portion of the pinion member,a flanged nut on the screw-threaded element, a body of elasticallydeformable material loosely mounted between said flanges, a barrelenclosing the flanges and elastically deformable material, and a detentmounted in the screw-threaded ele ment engaging the pinion to normallyretain it in idle position and to hold the pinion in engagement with theengine gear.

7. In an engine starter a power shaft, 2, flanged pinion member slidablyjournalled thereon to mesh with and rotate an engine gear, a flanged nutmember having a threaded connection with the power shaft, a cylinder ofelastically deforn e able material located between the flanges of thenut and the pinion and forming a yielding over running clutchtherebetween, a barrel member enclosing said flanges and cylinderslidably but non-rotatably connected to the pinion, and means forholding the pinion in mesh with the engine gear as long as the powershaft rotates above a predetermined speed.

8. In an engine starter, at power shaft, a pinion member slidablyjournalled thereon to mesh with and rotate an engine gear, a nut-memberhaving a threaded connection with the power shaft, a cylinder ofelastically deformable material lo cated between the nut and pinion andforming a yielding overrunning clutch therebetween, a barrel memberenclosing said cylinder and connecting the nut and pinion, and a detentin the path of the pinion rotatable with the power shaft and movable bycentrifugal force to engage the pinion and hold it in mesh with theengine gear JAMES E. BUXTON.

